Dear Edi, thank you for your question!
There are several limitations on this study.
The VUI is not a standardised instrument and was not tested on any psychometric criteria. Because the main point for the VUI was just a verbal basis. As you see I tested the sensitivity and the criterion-related validity of the PFUI, which were satisfactory, but they don't give a bigger picture on the psychometric criteria of the PFUI. As for future studies there needs to be more testing on main validity measures (as construct validity for example) and on reliability for both the VUI and the PFUI.
And as often the sample is also a limitation. We recruited our subjects mainly through social media and QR codes on flyers. This has two downsides:
1. In my opinion the PFUI can show its full potential when working with people who would profit from it the most; like adults with language comprehension problems as dyslexia, children and foreigners that don't speak the language good enough to understand verbal questionnaires. We probably did not have any subject that met one of those criteria. Especially when we restricted participation of people that didn't speak German fluently.... I think the problem here is very clear. For future research we should recruit in a broader sample and maybe even try to recruit people with those impairments and test specifically on this group.
2. Recruiting more people through with different approaches would probably solve the problem of the insignificant correlation between experience and usability judgement. Because of the pretty modern recruiting ways, we used, mainly people who are already experienced participated. This led to a very homogeneous group.
I hope I answered your questions, and if not, please don’t hesitate to ask further!
There are several limitations on this study.
The VUI is not a standardised instrument and was not tested on any psychometric criteria. Because the main point for the VUI was just a verbal basis. As you see I tested the sensitivity and the criterion-related validity of the PFUI, which were satisfactory, but they don't give a bigger picture on the psychometric criteria of the PFUI. As for future studies there needs to be more testing on main validity measures (as construct validity for example) and on reliability for both the VUI and the PFUI.
And as often the sample is also a limitation. We recruited our subjects mainly through social media and QR codes on flyers. This has two downsides:
1. In my opinion the PFUI can show its full potential when working with people who would profit from it the most; like adults with language comprehension problems as dyslexia, children and foreigners that don't speak the language good enough to understand verbal questionnaires. We probably did not have any subject that met one of those criteria. Especially when we restricted participation of people that didn't speak German fluently.... I think the problem here is very clear. For future research we should recruit in a broader sample and maybe even try to recruit people with those impairments and test specifically on this group.
2. Recruiting more people through with different approaches would probably solve the problem of the insignificant correlation between experience and usability judgement. Because of the pretty modern recruiting ways, we used, mainly people who are already experienced participated. This led to a very homogeneous group.
I hope I answered your questions, and if not, please don’t hesitate to ask further!